Canadian officials accelerated their plan to arrest the two suspects in an alleged plot to derail a passenger train traveling between Toronto and New York City, prompted by last week's bombing of the Boston Marathon and rebuffing U.S. requests to wait for further investigation, said two U.S. officials familiar with the probe.

Raed Jaser, 35 years old, and Chiheb Esseghaier, 30, were arrested Monday and accused of plotting an attack...